Something's off...

[jap7t8]

'90 650 SJ
Pretty much stock under the hood - only has MSD coil and wires
Rebuilt carb last summer and checked again this season - all looks good

Didn't touch the ski all winter (besides changing the fuel lines). Ive had it out 3 weekends this season and cant get the thing to run right. First it was fouling plugs like mad so I started tuning on the carb and cant seem to figure it out. Thought maybe it was stabilizer causing problems. It runs terribly for the first 5 minutes on the water. I have to run it really hard nonstop for a few minutes to clear out the plugs. The first time I slow down for a no wake zone or anything it starts acting up again. Im running both my needles at 3/4 turns out - 1.5 needle and seat. I've tried going rich and lean on each needle and cant seem to find a happy medium. Is 3/4 turn way off??? And its been hard to start on random occasions too.

Im at a total loss and need some advice. Any help would be appreciated.

 

[SUPERTUNE]

Start by getting a stock ignition coil!
The MSD RED replacement coils are not even good as a new OEM Yamaha stock one.
Healthy ignition is very important to the engine and carb settings.
In the meantime set the plug gap down to .022 thou.
Use non-resistor sparkplugs.

 

[sjetrider]

Huh, runs good on top and like shiot at bottom? Is it hard to start? If so check your reeds bro.

I agree wit Chuckey as well, DO NOT RUN the GARBAGE MSD COILS. They will make your life misserable. I run OEM coils on my TL.

 

[Buckwild12]

JSS coils fixed mll my previous issues.

 

[jap7t8]

Huh, runs good on top and like shiot at bottom? Is it hard to start? If so check your reeds bro.

I agree wit Chuckey as well, DO NOT RUN the GARBAGE MSD COILS. They will make your life misserable. I run OEM coils on my TL.

I know it's the strangest thing. I thought about the reeds too. Haven't checked them yet. It's only hard to start after it's been running for awhile...so when everything's hot. Starts right up when cold.

I'll look into a stock coil.

 

[chriselmore_1]

exhaust leak?

 

[jap7t8]

Haven't thought about exhaust leak either.

Is there any quick tricks to checking the reeds without pulling the mani? If I do have to, what do bad reeds look like?

Thanks for all the help! Heading to the lake this weekend and want to figure this thing out!

 

[baxt3r]

Bad reeds will be cracked or chipped. I'm sure there are other identifiers that someone will add.

 

[SUPERTUNE]

I know it's the strangest thing. I thought about the reeds too. Haven't checked them yet. It's only hard to start after it's been running for awhile...so when everything's hot. Starts right up when cold.

I'll look into a stock coil.

Could be carb flooding, try a rebuild with a Genuine Mikuni rebuit kit only with a new Mikuni needle valve. A leaky carb will have symptoms just like this, easy to start cold, harder to start when hot or after sitting for a few minutes.